function OpenWindow(url, w, h)
{
  x = (screen.width / 2) - (w / 2);
  y = (screen.height / 2) - (h / 2);
  features = "menubar=false,width=" + w + ",height=" + h + ",location=false,left=" + x + ",top=" + y;
  window.open(url, "", features);
}